The present invention is directed to systems and methods useful in testing for occult blood in a specimen. More particularly, the invention is directed to such systems and methods that are convenient and safe to use and provide accurate results.
Over 100,000 persons per year in the United States are afflicted with cancer of the colon and rectum, the disease, occurring equally in both men and women. When the number of colon/rectal cancers occurring each year is combined with the number of cancers occurring in other digestive organs, including the esophagus and stomach, such cancers of the digestive system account for more occurrences of cancer than any other single form of the disease. Contrary to many other forms of cancer, early diagnosis and treatment of digestive tract cancer does result in a cure rate of 80% to 90%. If, however, the disease is not detected until the later stages, the cure rate drops significantly. Thus, early detection of the disease is important to successful treatment of digestive tract cancer.
Most, but not all, cancers of the digestive tract bleed to a certain extent. This blood is deposited on and in fecal matter excreted from the digestive system. The presence of blood in fecal matter is not normally detected, however, until gross bleeding, that is, blood visible to the naked eye, occurs. Most advance cancers of this type cause gross bleeding.
It is known that digestive tract cancers in the early stages tend to bleed, giving rise to occult (hidden) blood in the fecal matter. Test equipment and test procedures have been developed for use by physicians in testing for the presence of occult blood in fecal matter. One of the most successful tests is manufactured and sold by Smith Kline Diagnostics of Sunnyvale, Calif. under the trademark HEMOCCULT and disclosed in Pagano U.S. Pat. No. 3,996,006, which is incorporated herein by reference in its entirety. Briefly, the Pagano test employs an absorbent paper impregnated with a guaiac reagent and encased in a special test slide having openable flaps on both sides of the test slide. To use the Pagano test slide, the physician or a lab technician must obtain a sample of fecal matter, smear it onto the guaiac impregnated paper by opening the panel on one side of the test slide, and thereafter close the panel. A panel on the opposite side of the test slide is then opened and a nonaqueous developing solution is applied to the guaiac impregnated paper. If occult blood is present in the fecal matter smeared on the opposite side of the paper, the guaiac reaction will dye the paper blue, providing a positive indication of the presence of blood in the fecal matter.
Although the Pagano test is effective when used by physicians in their offices and by diagnostic laboratories, it is not the type of test which is readily adaptable for use by the ordinary person. It is cumbersome and requires too many manipulative steps, particularly the step of applying the nonaqueous developing solution to the guaiac impregnated paper.
Schreiber U.S. Pat. No. 5,171,529, which is incorporated herein by reference in its entirety, discloses a device that eliminates the need to have a separate container of developing solution. An absorbent pad holding the developing solution is integrated into the device. After a specimen is placed on one side of the testing paper, the absorbent pad is drawn across the opposing side of the testing paper. While the pad is being drawn across the testing paper, developing solution in the pad is transferred to the testing paper. The testing paper is then observed, for example, visually observed, to determine if a color change has occurred, which indicates the presence of occult blood. However, sufficient and consistent transfer of the developing solution from the absorbent pad to the testing paper is questionable. Further, the used absorbent pad extends from the device disclosed in Schreiber, exposing the user to the developing solution and the contamination on the pad. The developing solution, as with many types of kits, is very reactive and must not be splashed or rubbed on sensitive skin or eyes.
It would be advantageous to provide a system and method, for testing for occult blood, for example, fecal occult blood, that reduces, or even eliminates, the exposure of the user to developing solution that is contaminated with the specimen. Further, it would be advantageous to provide for testing for occult blood that integrates the delivery of the developing solution and the testing paper to reduce system/method complexity and reduce the need for manual dexterity, while providing accurate and reliable results.
Self-contained systems and methods for testing for the presence of occult blood in a specimen have been discovered. Such systems integrate the developing medium, the delivery of the developing medium, and the testing paper. The present systems eliminate the need for a separate container of developing medium. Such systems also eliminate specimens, for example, fecal matter, splashing onto the system user during and after application of the developing medium in the presence of the specimen.
In one broad aspect of the invention, the present systems comprise a test matrix, a container and a housing. The test matrix includes a testing portion having a specimen placement area on one side and a result area on an opposing second side. In one embodiment, the test portion is offset or spaced apart from a medium entrance portion. The container holds a developing medium and is adapted to release the developing medium onto the test matrix, for example, initially onto the medium entrance portion of the text matrix. The housing holds the test matrix and the container, and includes an opening at the specimen placement area. A result viewing means can be provided for observing the result area. The result viewing means may be an opening in the housing at the result area, or a transparent portion of housing disposed over the result area. The housing preferably further includes a viewing opening located at, that is in line with, the result area of the test matrix. In a more preferred aspect of the invention, a film is disposed across the viewing opening that enables the user to see the result area while inhibiting the developing medium or the fecal sample from escaping through the viewing opening.
Preferably, the container is enclosed by the housing. The container preferably is adapted to release the developing medium upon compression of the container, for example, by applying manual compressive force to the housing. More preferably, the container is adapted to release the developing medium upon breaking the container. In this embodiment a container made of glass is very useful. The housing advantageously comprises a cover for the specimen placement area.
In one embodiment of the invention, the test matrix further comprises a validation area adapted to verify that the system, including the test matrix and the developing medium, is effective, for example, to interact and to indicate the presence of occult blood. The housing preferably comprises a validation viewing means for observing the validation area. The validation viewing means may be an opening in the housing at the validation area or a transparent portion of the housing disposed over the validation area. In a more preferred aspect of the invention, a film, such as a transparent polymeric film, is disposed across the opening that enables the user to see the validation area while inhibiting the developing medium from escaping through the opening.
Preferably, the validation area is closer to the medium entrance portion of the test matrix than is the testing portion. More preferably, a majority of the medium entrance portion is between the testing portion and the validation area of the test matrix.
In one very useful embodiment of the invention, the container holds a free standing liquid developing medium and is positioned and adapted to release the liquid developing medium onto the test matrix. As used herein, the term xe2x80x9cfree standing liquidxe2x80x9d refers to a material which is present as a liquid without being absorbed on an absorbent material. In other words, a xe2x80x9cfree standing liquidxe2x80x9d is a material which preferably is readily visually perceived as being in the liquid phase. The term xe2x80x9cfree standing liquidxe2x80x9d is clearly distinguished from the absorbed developing solution of Schreiber U.S. Pat. No. 5,171,529, noted above.
In another aspect of the present invention, methods for testing for the presence of occult blood in a specimen are provided. Such methods comprise providing a self-contained system including a housing holding a test matrix and a container. The test matrix comprises a testing portion having a specimen placing area on a first side and a result area on a opposing second side. The container holds a developing medium, for example, a free standing liquid developing medium, e.g., developing solution or reagent. The container is adapted to release the developing medium onto the test matrix. The housing includes a specimen opening at the specimen placement area. The present methods further include placing a specimen, for example, of fecal matter, on the specimen placement area; releasing the developing medium from the container onto the test matrix; and observing the result area, for example, the color of the result area, to provide an indication of occult blood in the specimen. The present systems are particularly useful in practicing the present methods.
In a particularly useful embodiment, the present releasing step occurs prior to the placing step. It has been found that releasing the developing medium prior to placing the specimen on the specimen placing area provides for very effective and reliable results. Without wishing to limit the invention to any particular theory of operation, it is believed that releasing the developing medium prior to placing the specimen on the specimen placing area enhances the ability of the developing medium and the test matrix to interact with the specimen in providing an indication of occult blood in the specimen.
Each and every feature and combination of two or more features described herein is included within the scope of the present invention provided that the features included in the combination are not mutually inconsistent.
These and other aspects and advantages of the present invention are set forth in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.